Axial magnetic suspension

ABSTRACT

The present invention generally relates to an apparatus and method for axially supporting a shaft. In one aspect, a magnetic suspension system for supporting a shaft in a housing is provided. The magnetic suspension system includes an array of magnet members disposed between the shaft and the housing. The array of magnet members comprising a first magnet member, a second magnet member, and a third magnet member, wherein the first magnet member and the second magnet member generate a first force that is substantially parallel to a longitudinal axis of the shaft and the second magnet member and the third magnet member generate a second force that is substantially parallel with the longitudinal axis of the shaft The first force and the second force are configured to position the shaft axially within the housing. In another aspect, a method of supporting a shaft along a longitudinal axis of a housing is provided. In a further aspect, a suspension system for supporting a shaft in a housing is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/356,572, filed Jun. 19, 2010, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to the support ofmachinery. More particularly, the invention relates to an apparatus andmethod for axially supporting a shaft or other mass that is laterallysupported.

2. Description of the Related Art

A conventional magnetic suspension assembly is based on the repulsiveforce which exists between two similar magnetic poles. An example of aconventional magnetic suspension assembly is illustrated in FIG. 1. Asshown, the conventional magnetic suspension assembly 10 includes a shaft15 disposed within a housing 20. As illustrated, a first pair ofopposing magnets 25, 30 is positioned on one end of the rotating shaft15 and a second pair of opposing magnets 35, 40 at another end of therotating shaft 15, suspending the shaft 15. Note that radial supportmust be provided by other means to prevent lateral movement and cockingof the suspended structure. This radial support can be provided byseveral means including conventional bearings or bushings.

As greater and greater loads are placed on the suspended structure, itbecomes necessary to increase the magnetic field strength. This can beaccomplished by increasing the volume of magnetic material througheither increasing the size or adding duplicate pairs of magnets (e.g.,magnets 25, 30). Due to structural and form factor machine constraints,it is often not possible to increase the face surface area of themagnets, but rather the depth or thickness must be increased. This isonly possible until the thickness is on the order of the face width asfurther magnetic material added is further away from the active face andis decreased by 1/R. As this limit is approached, one must addadditional magnetic pairs. There is a need for a more efficient use ofmagnetic material to create the increased strength with balance.

SUMMARY OF THE INVENTION

The present invention generally relates to an apparatus and method foraxially supporting a shaft. In one aspect, a magnetic suspension systemfor supporting a shaft in a housing is provided. The magnetic suspensionsystem includes an array of magnet members disposed between the shaftand the housing. The array of magnet members comprising a first magnetmember, a second magnet member, and a third magnet member, wherein thefirst magnet member and the second magnet member generate a first forcethat is substantially parallel to a longitudinal axis of the shaft andthe second magnet member and the third magnet member generate a secondforce that is substantially parallel with the longitudinal axis of theshaft The first force and the second force are configured to positionthe shaft axially within the housing.

In another aspect, a method of supporting a shaft along a longitudinalaxis of a housing is provided. The method includes the step of selectingan axial position of the shaft within the housing. The method furtherincludes the step of selecting an array of magnet members based upon theselected axial position. Additionally, the method includes the step ofpositioning the array of magnet members between the shaft and thehousing such that a first force and a second force are generated in thearray of magnet members which is configured to position the shaft at theaxial position within the housing.

In a further aspect, a suspension system for supporting a shaft in ahousing is provided. The system includes a first array of magnet membersdisposed between the shaft and the housing at one end of the shaft. Thesystem further includes a second array of magnet members disposedbetween the shaft and the housing at another end of the shaft, whereinthe first array of magnet member generates first and second forces andthe second array of magnet members generates third and fourth forces andwherein the forces are configured to position the shaft axially withinthe housing.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a view illustrating a conventional magnetic suspensionassembly known in the art.

FIG. 2 is a view illustrating a magnetic suspension assembly of thepresent invention.

FIG. 3 is a view illustrating a magnetic suspension assembly.

FIG. 4 is a view illustrating a force diagram in the magnetic suspensionassembly shown in FIG. 3.

FIG. 5 is a graph that illustrates a displacement from rest based uponan axial load applied to a shaft of the magnetic suspension assemblyshown in FIG. 4.

FIG. 6 is a view illustrating a force diagram of a magnetic suspensionassembly.

FIG. 7 is a graph that illustrates the displacement from rest based uponan axial load applied to a shaft of the magnetic suspension assemblyshown in FIG. 6.

FIG. 8 is a view illustrating a force diagram of a magnetic suspensionassembly.

FIG. 9 is a graph that illustrates the displacement from rest based uponan axial load applied to a shaft of the magnetic suspension assemblyshown in FIG. 8.

FIG. 10 is a view illustrating a force diagram of a magnetic suspensionassembly.

FIG. 11 is a graph that illustrates the displacement from rest basedupon an axial load applied to a shaft of the magnetic suspensionassembly shown in FIG. 10.

FIG. 12 is a view illustrating a magnetic suspension assembly.

DETAILED DESCRIPTION

The present invention is generally directed to a suspension assemblywhich can be selected based upon desired design parameters. Thesuspension assembly will be described herein in relation to rotatingmachinery, such as turbines. It is to be understood, however, that thesuspension assembly may also be used for other types of machinerywithout departing from principles of the present invention and thatshaft or housing rotation is not required. Vertical support of variableload masses is also to be considered part of the present invention.Additionally, the suspension system will be described in relation tomembers that are made from magnetic materials. It is to be understood,however, that the members may be made from other materials that areconfigured to generate forces on adjacent members. To better understandthe novelty of the suspension assembly of the present invention and themethods of use thereof, reference is hereafter made to the accompanyingdrawings. The present invention depicts the use of permanent magnets,however the present invention can also use electromagnets or acombination of permanent and electromagnets. The combination ofelectromagnets allows for controlled axial positioning with variableloading.

FIG. 2 is a view illustrating a magnetic suspension assembly 100 of thepresent invention. The assembly 100 includes a shaft 105 disposed withina housing 110. The shaft 105 is configured to rotate relative to thehousing 110. The shaft 105 is radially supported by bearings (notshown). The shaft 105 is also configured to move axially relative to thehousing 110. As will be described herein, the shaft 105 is axiallysupported by a plurality of magnet members. The magnet members may beselected and arranged to achieve a desired design parameter. Forinstance, the magnet members may be selected and arranged such that theshaft is automatically centralized in the housing as set forth in theembodiment shown in FIGS. 3-5. Further, the magnet members may beselected and arranged such that the shaft requires an axial load to becentralized in the housing as set forth in the embodiment shown in FIGS.6 and 7. Furthermore, the magnet members may be selected and arrangedsuch that the shaft is automatically offset in the housing as set forthin the embodiment shown in FIGS. 8 and 9. In other words, magneticdirections, strength and face to face spacing would be chosen to yieldthe desired response of the shaft.

As shown in FIG. 2, the magnetic suspension assembly 100 includes anarray of magnet members comprising a first magnet member 115, a secondmagnet member 120 and a third magnet member 125. The first magnet member115 and the third magnet member 125 are attached to the housing 110, andthe second magnet member is attached to the shaft 105. In an alternativeembodiment, the first magnet member 115 and the third magnet member 125are attached to the shaft 105, and the second magnet member is attachedto the housing 110. As shown, the second magnet member 120 is disposedbetween the first magnet member 115 and the third magnet member 125. Thepolarity of the magnet members 115, 120, 125 is arranged such that thesecond magnet member 120 is centralized between the first magnet member115 and the third magnet member 125. The magnet members 115, 120, 125are shown as rings with a rectangular cross-section. It should beunderstood, however, that the magnet members 115, 120, 125 may have anygeometrical shape and cross-section, without departing from principlesof the present invention and that centralized spacing is not required.

As shown in FIG. 2, the magnet member 120 attached to the shaft 105 issurrounded on both sides by magnet members 115, 125 which are fixed inthe housing 110. In the case where adjacent magnet members generaterepulsive forces, the magnet member 120 and shaft 105 will be suspendedin an axial sense.

FIG. 3 is a view illustrating a magnetic suspension assembly 150 of thepresent invention. As shown, the assembly 150 includes a first array ofmagnet members comprising first, second and third magnet members 165,170, 175 on one side of the shaft 155 and a second array of magnetmembers comprising fourth, fifth and sixth magnet members 185, 190, 195on the other side of the shaft 155. The shaft 155 is configured torotate relative to a housing 160. The shaft 155 is radially supported bybearings (not shown) and axially supported by the magnet members 165,170, 175, 185, 190, 195. As shown, the magnet members 170, 190 areattached to the housing 160, and the magnet members 165, 175 areattached to the shaft 155. In another embodiment, the magnet members170, 190 are attached to the shaft 155, and the magnet members 165, 175are attached to the housing 160.

A north magnetic pole (N) and a south magnetic pole (S) are shown ineach magnet member. The magnet members are arranged such that themagnetic poles for adjacent magnet members are the same. For instance,the south magnetic pole of the first magnet member 165 is facing thesouth magnetic pole of the second magnet member 170, and as such arepulsive force is generated between the first and second magnet members165, 170. As illustrated, a similar arrangement is between the othermagnet members in the magnetic suspension assembly 150. In other words,the center magnet member (e.g., the second magnet member 170 and thefifth magnet member 190) is effectively held in balance between therepulsive forces of the outer magnet members.

One aspect of the magnet arrays is a more efficient use of magneticmaterial to create the increased strength with balance. As shown in FIG.3, by adding a third magnet member but in a reverse sense, the centermagnet member is effectively held in balance between the repulsiveforces of the outer magnet members. By placing a second magnet memberarray that is balanced by magnet members at the opposite end of theshaft, one can create a stable balanced system with twice the strengthof using only six magnet members.

FIG. 4 is a view illustrating a force diagram in the magnetic suspensionassembly 150. As shown, repulsive forces (Fa and Fb) are applied to thefifth magnetic 190 by the fourth magnet member 185 and the sixth magnetmember 195. Repulsive forces (Fc and Fd) are applied to the secondmagnet member 170 by the first magnet member 165 and the third magnetmember 175.

Initial Conditions: d1=d2=S

Axial Load=Fa−Fb+Fc−Fd

Axial Load=2Fa−2Fb due to symmetry and

d1=S+X

d2=S−X

Note: Positive X is to the Right

FIG. 5 is a graph that illustrates the displacement from rest based uponan axial load applied to the shaft 155. Line 180 illustrates the shaft155 at rest when no axial load is applied to the shaft 155. Asillustrated, the shaft 155 is centralized in a stable balanced systemwith 0 axial load and 0 displacement. The stable balanced system occurswhen d1=d2 and the magnet members 165, 170, 175, 185, 190, 195 have thesame magnetic strength due to similar volume, internal composition anddensity of magnetic material. An axial load may be applied to the shaft155, which results in the shaft 155 being moved (or displaced) from thecentralized position. For example, an axial load of approximately 55pounds applied to the shaft 155 results in a displacement ofapproximately 0.12 inches in the −X direction (see point 135). Inanother example, an axial load (in direction opposite the axial loadarrow) of approximately 50 pounds applied to the shaft 155 will resultin a displacement of approximately 0.08 inches in the +X direction (seepoint 130). The embodiment shown in the FIGS. 4-6 illustrates a balancedsuspension system. In one embodiment, using individual magnet members ofapproximately 40 pounds force repulsion, it is possible to create abalanced suspension system with approximately 80 peak load capacity.

FIG. 6 is a view illustrating a force diagram of a magnetic suspensionassembly 200. As shown, the assembly 200 includes a first array ofmagnet members comprising first, second and third magnet members 215,220, 225 on one side of the shaft 205 and a second array of magnetmembers comprising fourth, fifth and sixth magnet members 235, 240, 245on the other side. The shaft 205 is configured to rotate relative to ahousing 210. The shaft 205 is radially supported by bearings (not shown)and axially supported by the magnet members 215, 220, 225, 235, 240,245. As shown, the magnet members 220, 240 are attached to the housing210 and the magnet members 235, 245 are attached to the shaft 205. Inanother embodiment, the magnet members 220, 240 are attached to theshaft 205, and the magnet members 235, 245 are attached to the housing210.

The magnet members are arranged such that some magnetic poles foradjacent magnet members are the same and some magnetic poles foradjacent magnet members are different. For instance, the north magneticpole of the first magnet member 215 is facing the north magnetic pole ofthe second magnet member 220, and as such a repulsive force is generatedbetween the first and second magnet members 215, 220. Additionally, thesouth magnetic pole of the second magnet member 220 is facing the northmagnetic pole of the third magnet member 225, and as such an attractiveforce is generated between the first and second magnet members 215, 220.A similar arrangement is between the fourth, fifth and sixth magnetmembers 235, 240, 245. The center magnet member (e.g., the second magnetmember 220 and the fifth magnet member 240) is being repulsed by somemagnet members and attracted by other magnet members in the samedirection.

As shown in FIG. 6, forces (Fa and Fb) are applied to the fifth magnetic240 by the fourth magnet member 235 and the sixth magnet member 245.Forces (Fc and Fd) are applied to the second magnetic 220 by the firstmagnet member 215 and the third magnet member 225.

Axial Load=Fa+Fb+Fc+Fd

Axial Load=2Fa+2Fb due to symmetry

Note: Positive X is to the Right

FIG. 7 is a graph that illustrates the displacement from rest based uponan axial load applied to the shaft 205. As illustrated, the shaft 205 isat point 260 (e.g., 0 displacement) when an applied axial load ofapproximately 75 pounds is applied to the shaft 205. In other words, anaxial load must be applied to the shaft 205 to position the shaft 205 atthe point 260. A symmetric arrangement around the point 260 occurs whenthe magnet members 215, 220, 225, 235, 240, 245 have the same magneticstrength due to similar volume, internal composition and density ofmagnetic material. For example, the shaft 205 having a 0.12 displacementin the +X direction requires an axial force of approximately 95 pounds(see point 230) and the shaft having a 0.12 displacement in the −Xdirection requires an axial force of approximately 95 pounds (see point255). Thus, the magnetic suspension assembly 200 has the sameperformance in the −X direction and +X direction for the samedisplacement relative to the point 260. In this manner, the magneticsuspension assembly 200 can be configured to require a minimum load forfirst movement, but has equal force displacement relationship in eitherdirection.

FIG. 8 is a view illustrating a force diagram of a magnetic suspensionassembly 300 of the present invention. The magnetic suspension assembly300 is configured to have an asymmetric mechanical response. As shown,the assembly 300 includes a first array of magnet members comprisingfirst, second and third magnet members 315, 320, 325 on one side of theshaft 305 and a second array of magnet members comprising fourth, fifthand sixth magnet members 335, 340, 345 on the other side. The shaft 305is configured to rotate relative to a housing 310. The shaft 305 isradially supported by bearings (not shown) and axially supported by themagnet members 315, 320, 325, 335, 340, 345. As shown, the magnetmembers 320, 340 are attached to the housing 310, and the magnet members315, 325, 335, 345 are attached to the shaft 305. In another embodiment,the magnet members 320, 340 are attached to the shaft 305, and themagnet members 315, 325, 335, 345 are attached to the housing 310.

The magnet members 315, 320, 325, 335, 340, 345 are arranged such thatthe magnetic poles for adjacent magnet members are the same. Thus,repulsive forces (Fa and Fb) are applied to the fifth magnet member 340by the fourth magnet member 335 and the sixth magnet member 345, andrepulsive forces (Fc and Fd) are applied to the second magnet member 320by the first magnet member 315 and the third magnet member 325. Asillustrated, the third magnet member 325 and the sixth magnet member 345are larger than the other magnet members and therefore have a largermagnetic strength. In one embodiment, the third magnet member 325 andthe sixth magnet member 345 are twice as large as the other magnetmembers.

Axial Load=Fa−Fb+Fc−Fd

Axial Load=2Fa−2Fb due to symmetry

d1=S+X

d2=S−X

Note: Positive X is to the Right

The distance d1 between same-sized magnet members (e.g., first magnetmember 315 and second magnet member 320) is not equal to the distance d2between different-sized magnet members (e.g., second magnet member 320and third magnet member 325) due to unequal strength of the magnetmembers. In another embodiment, the first magnet member 315 and thefourth magnet member 335 are larger than the other magnet members andtherefore have a larger magnetic strength.

The magnetic suspension assembly 300 with the asymmetric mechanicalresponse can be accomplished by varying the magnetic strength ofspecific magnet members in the magnetic suspension assembly 300. Thiscan be accomplished by increasing the volume of the magnet member, bychanging its internal composition, or density of magnetic material. Asshown FIGS. 8 and 9, by doubling the strength of the leftmost leadmagnet member (e.g., magnet members 325, 345) on both sides of the shaft305, the load force can be increased in one direction but not thereverse. In this example, the device can support loads up to 120 poundsin the −X direction and only 75 pounds in the +X direction. This featurecan be very useful in applications where the load is asymmetric or wherethe weight of the structure must be added to the dynamic loads expected.Indeed, by varying the various magnetic components and their relativespacing, the suspension can be fine-tuned for a specific application.

FIG. 9 is a graph that illustrates the displacement from rest based uponan axial load applied to the shaft 305. Line 330 illustrates the shaft305 at rest when no axial load is applied to the shaft 305. Asillustrated in the graph, the shaft 305 is centralized in a stablebalanced system with 0 axial load and 0.05 inches of displacement in the+X direction. The reason the shaft 305 is centralized at the 0.05 inchesof displacement in the +X direction is because the repulsive forces Fa,Fc of the (larger) magnet members 345, 325, respectively, are strongerthan the repulsive forces Fb, Fd of the (smaller) magnet members 335,315, respectively. As also illustrated in the graph, a greater force isrequired to displace the shaft 305 in the −X direction than +X directionfor the same displacement. For example, the shaft having a 0.125displacement in the −X direction requires an axial force ofapproximately 75 pounds (see point 365), and the shaft 305 having a0.125 displacement in the +X direction requires an axial force (in adirection opposite the axial load arrow) of approximately 38 pounds (seepoint 360). Thus, the magnetic suspension assembly 300 has differentperformance in the −X direction and +X direction for the same amount ofdisplacement.

FIG. 10 is a view illustrating a force diagram of a magnetic suspensionassembly 400 of the present invention. As shown, the assembly 400includes a first array of magnet members comprising first, second, thirdand fourth magnet members 415, 420, 425, 430 on one side of a shaft 405and a second array of magnet members comprising fifth, sixth, seventhand eighth magnet members 435, 440, 445, 450 on the other side. Theshaft 405 is configured to rotate relative to a housing 410. The shaft405 is radially supported by bearings (not shown) and axially supportedby the magnet members 415, 420, 425, 430,435, 440, 445, 450. As shown,the magnet members 415, 425, 435 and 445 are attached to the housing 410and the magnet members 420, 430, 440, 450 are attached to the shaft 405.In another embodiment, the magnet members 415, 425, 435 and 445 areattached to the shaft 405 and the magnet members 420, 430, 440, 450 areattached to the housing 410.

The magnet members are symmetric and may be arranged to have bothattractive forces and repulsive forces. The forces will be explained inrelation to the first magnetic array consisting of the first, second,third and fourth magnet members 415, 420, 425, 430. It is to beunderstood the forces on the second magnetic array consisting of thefifth, sixth, seventh and eighth magnet members 435, 440, 445, 450 willbe the same. As shown, forces Fd, Fe and Ff are repulsive forces becauseadjacent magnet members have the same polarity (e.g., N/N or S/S). Inaddition to the respective polarities, the first magnet member 415 andthe fourth magnet member 430 are larger than the second magnet member420 and the third magnet member 435, which results in unequal forcesbetween the magnet members.

FIG. 11 is a graph that illustrates the displacement from rest basedupon an axial load applied to the shaft 405. Line 460 illustrates theshaft 405 at rest when no axial load is applied to the shaft 405. Asillustrated in the graph, the shaft 405 is displaced approximately 0.12inches in the +X direction when the shaft is in a stable balanced systemwith 0 axial load. The reason the shaft 405 is centralized at the 0.12inches in the +X direction is because the repulsive force Fd and theattractive forces Ff are greater than the repulsive force Fe. As alsoillustrated in the graph, a greater force is required to displace theshaft 405 in the −X direction than +X direction for the samedisplacement. For example, the shaft having a 0.17 displacement in the−X direction requires an axial force of approximately 200 pounds (seepoint 475), and the shaft 405 having a 0.17 displacement in the +Xdirection requires an axial force (in a direction opposite the axialload arrow) of approximately 30 pounds (see point 470). Thus, themagnetic suspension assembly 400 has different displacement performancein the −X direction and +X direction for the same amount ofdisplacement.

In some applications, the restriction of space for magnetic material andthe specific load requirements will only be met by increasing the numberof magnetic elements in the suspension system. FIGS. 10 and 11 show amathematical model for a magnetic suspension assembly 400 with 4magnetic masses (on each side), sized and spaced to create a largeasymmetrical load-bearing for an application where there is insufficientspace for a single large magnet member. In the example, magnet membersof 2× strength are used as outer members of asymmetrical arrays (e.g.,the first array and the second array). The resulting performance gives aload response greater than 4:1 in the axial direction.

FIG. 12 is a view illustrating a magnetic suspension assembly 500 of thepresent invention. The assembly 500 includes a shaft 505 disposed withina housing 510. Similar to other embodiments, the shaft 505 is configuredto rotate relative to the housing 510. The shaft 505 is radiallysupported by bearings (not shown) and axially supported by a symmetricarray of magnet members 515, 520, 525, 530, 535. As shown, the magnetmembers are arranged in an alternating manner such that adjacent magnetmembers are attached to the housing 510 (or the shaft 505). Forinstance, magnet member 515 is attached to the housing 515 and adjacentmagnet member 520 is attached to the shaft 505 and so forth.Additionally, the magnet members 515, 520, 525, 530, 535 are equallyspaced relative to each other and the magnet members 515, 520, 525, 530,535 have the same size. In one embodiment, the adjacent magnet membersare arranged to have the same polarity such that the shaft 505 iscentralized in the housing 510 (similar to FIG. 3). In anotherembodiment, the adjacent magnet members are arranged to have theopposite polarity such that the shaft 505 is offset to one side of thehousing 510 (similar to FIG. 6). In a further embodiment, the adjacentmagnet members are arranged to have alternating polarity. In otherwords, magnetic directions, strength and spacing would be chosen toyield the desired response of the shaft.

In one embodiment, a magnetic suspension system for supporting a shaftin a housing is provided. The magnetic suspension system includes anarray of magnet members disposed between the shaft and the housing. Thearray of magnet members comprising a first magnet member, a secondmagnet member, and a third magnet member, wherein the first magnetmember and the second magnet member generate a first force that issubstantially parallel to a longitudinal axis of the shaft and thesecond magnet member and the third magnet member generate a second forcethat is substantially parallel with the longitudinal axis of the shaftThe first force and the second force are configured to position theshaft axially within the housing.

In another embodiment, a method of supporting a shaft along alongitudinal axis of a housing is provided. The method includes the stepof selecting an axial position of the shaft within the housing. Themethod further includes the step of selecting an array of magnet membersbased upon the selected axial position. Additionally, the methodincludes the step of positioning the array of magnet members between theshaft and the housing such that a first force and a second force aregenerated in the array of magnet members which is configured to positionthe shaft at the axial position within the housing.

In another embodiment, a suspension system for supporting a shaft in ahousing is provided. The system includes a first array of magnet membersdisposed between the shaft and the housing at one end of the shaft. Thesystem further includes a second array of magnet members disposedbetween the shaft and the housing at another end of the shaft, whereinthe first array of magnet member generates first and second forces andthe second array of magnet members generates third and fourth forces andwherein the forces are configured to position the shaft axially withinthe housing.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A magnetic suspension system for supporting a shaft in a housing, thesystem comprising: an array of magnet members disposed between the shaftand the housing, the array of magnet members comprising a first magnetmember, a second magnet member, and a third magnet member, wherein thefirst magnet member and the second magnet member generate a first forcethat is substantially parallel to a longitudinal axis of the shaft andthe second magnet member and the third magnet member generate a secondforce that is substantially parallel with the longitudinal axis of theshaft and wherein the first force and the second force are configured toposition the shaft axially within the housing.
 2. The magneticsuspension system of claim 1, wherein the first magnet member and thethird magnet member are attached to the housing and the second magnetmember is attached to the shaft.
 3. The magnetic suspension system ofclaim 3, wherein the second magnet member is disposed between the firstmagnet member and the third magnet member.
 4. The magnetic suspensionsystem of claim 1, wherein the first force is in one direction and thesecond force is in an opposite direction and the first and second forcesare substantially equal which causes the shaft to be centralized withinthe housing.
 5. The magnetic suspension system of claim 1, wherein thefirst force is in one direction and the second force is in an oppositedirection and the first and second forces are unequal which causes theshaft to be offset within the housing.
 6. The magnetic suspension systemof claim 1, wherein the third magnet member is twice the size of eitherthe first magnet member or the second magnet member.
 7. The magneticsuspension system of claim 6, wherein a distance between the thirdmagnet member and the second magnet member is greater than a distancebetween the second magnet member and the first magnet member.
 8. Themagnetic suspension system of claim 1, further comprising a second arrayof magnet members disposed between the shaft and the housing, the secondarray of magnet members comprising a fourth magnet member, a fifthmagnet member, and a sixth magnet member.
 9. The magnetic suspensionsystem of claim 8, wherein the array of magnet members are disposedproximate a first end of the shaft and the second array of magnetmembers are disposed proximate a second end of the shaft.
 10. Themagnetic suspension system of claim 9, wherein the fourth magnet memberand the fifth magnet member generate a third force that is substantiallyparallel to the longitudinal axis of the shaft and the fifth magnetmember and the sixth magnet member generate a fourth force that issubstantially parallel with the longitudinal axis of the shaft.
 11. Themagnetic suspension system of claim 10, wherein the first force and thethird force are in one direction and the second force and the fourthforce are in an opposite direction and the forces are substantiallyequal which causes the shaft to be centralized within the housing. 12.The magnetic suspension system of claim 10, wherein the first force andthe third force are in one direction and the second force and the fourthforce are in an opposite direction and the forces are unequal whichcauses the shaft to be offset within the housing.
 13. A method ofsupporting a shaft along a longitudinal axis of a housing, the methodcomprising: selecting an axial position of the shaft within the housing;selecting an array of magnet members based upon the selected axialposition; and positioning the array of magnet members between the shaftand the housing such that a first force and a second force are generatedin the array of magnet members which is configured to position the shaftat the axial position within the housing.
 14. The method of claim 13,wherein the array of magnet members comprises a first magnet member, asecond magnet member, and a third magnet member.
 15. The method of claim14, further comprising attaching the first magnet member and the thirdmagnet member to the housing and the second magnet member to the shaft.16. The method of claim 14, wherein the second magnet member is disposedbetween the first magnet member and the third magnet member.
 17. Themethod of claim 13, wherein selecting the array of magnet membersincludes selecting a density of magnetic material for each magnetmember.
 18. The method of claim 13, wherein selecting the array ofmagnet members includes selecting spacing between magnet members in thearray of magnet members.
 19. The method of claim 13, wherein the firstforce is in one direction and the second force is in an oppositedirection and the first and second forces are substantially equal whichcauses the shaft to be centralized within the housing.
 20. A suspensionsystem for supporting a shaft in a housing, the system comprising: afirst array of magnet members disposed between the shaft and the housingat one end of the shaft; and a second array of magnet members disposedbetween the shaft and the housing at another end of the shaft, whereinthe first array of magnet member generates first and second forces andthe second array of magnet members generates third and fourth forces andwherein the forces are configured to position the shaft axially withinthe housing.
 21. The system of claim 20, wherein each array of magnetmembers includes at least three magnet members.